A remote or central computer that holds electronic mail (e-mail) messages for clients on a network is called a mail server. A mail server is similar to the post office, where mail is stored and sorted before being sent to its final destination. When the user requests his or her e-mail, contact is established with the mail server, which then delivers all stored to the client's computer.
What is my mail server address?
Your mail server address and other information should be provided by your e-mail provider. Typically this information is either found on the e-mail providers support page or in documentations from your e-mail provider. On your e-mail provider's website, the information may be listed as SMTP and POP3 addresses.
Mail server information is often configured in a website's cPanel, or equivalent interface.